/Engine/Source/Runtime/Engine/Classes/Kismet/KismetRenderingLibrary.h
Changes the resolution of a render target. This is useful for when you need to resize the game viewport or change the in-game resolution during runtime and thus need to update the sizes of all the render targets in the game accordingly.
static void ResizeRenderTarget2D ( [UTextureRenderTarget2D](API\Runtime\Engine\Engine\UTextureRenderTarget2D) * TextureRenderTarget, int32 Width, int32 Height )